1. Field of the Invention
This invention relates to electroluminescent complexes of iridium(III) with fluorinated phenylpyridines, phenylpyrimidines, and phenylquinolines. It also relates to electronic devices in which the active layer includes an electroluminescent Ir(II) complex.
2. Description of the Related Art
Organic electronic devices that emit light, such as light-emitting diodes that make up displays, are present in many different kinds of electronic equipment. In all such devices, an organic active layer is sandwiched between two electrical contact layers. At least one of the electrical contact layers is light-transmitting so that light can pass through the electrical contact layer. The organic active layer emits light through the light-transmitting electrical contact layer upon application of electricity across the electrical contact layers.
It is well known to use organic electroluminescent compounds as the active component in light-emitting diodes. Simple organic molecules such as anthracene, thiadiazole derivatives, and coumarin derivatives are known to show electroluminescence. Semiconductive conjugated polymers have also been used as electroluminescent components, as has been disclosed in, for example, Friend et al., U.S. Pat. No. 5,247,190, Heeger et al., U.S. Pat. No. 5,408,109, and Nakano et al., Published European Patent Application 443 861. Complexes of 8-hydroxyquinolate with trivalent metal ions, particularly aluminum, have been extensively used as electroluminescent components, as has been disclosed in, for example, Tang et al., U.S. Pat. No. 5,552,678.
Burrows and Thompson have reported that fac-tris(2-phenylpyridine) iridium can be used as the active component in organic light-emitting devices. (Appl. Phys. Lett. 1999, 75, 4.) The performance is maximized when the iridium compound is present in a host conductive material. Thompson has further reported devices in which the active layer is poly(N-vinyl carbazole) doped with fac-tris[2-(4xe2x80x2,5xe2x80x2-difluorophenyl)pyridine-Cxe2x80x22,N]iridium(III). (Polymer Preprints 2000, 41(1), 770.)
However, there is a continuing need for electroluminescent compounds having improved efficiency.
The present invention is directed to an iridium compound (generally referred as xe2x80x9cIr(III) compoundsxe2x80x9d) having at least two 2-phenylpyridine ligands in which there is at least one fluorine or fluorinated group on the ligand. The iridium compound has the following First Formula:
IrLaLbLcxLxe2x80x2yLxe2x80x3zxe2x80x83xe2x80x83(First Formula) 
where:
x=0 or 1, y=0, 1 or 2, and z=0 or 1, with the proviso that:
x=0 or y+z=0 and
when y=2 then z=0;
Lxe2x80x2=a bidentate ligand or a monodentate ligand, and is not a phenylpyridine, phenylpyrimidine, or phenylquinoline; with the proviso that:
when Lxe2x80x2 is a monodentate ligand, y+z=2, and
when Lxe2x80x2 is a bidentate ligand, z=0;
Lxe2x80x3=a monodentate ligand, and is not a phenylpyridine, and phenylpyrimidine, or phenylquinoline; and
La, Lb and Lc are alike or different from each other and each of La, Lb and Lc has structure (I) below: 
wherein:
adjacent pairs of R1 through R4 and R5 through R8 can be joined to form a five- or six-membered ring,
at least one of R1 through R8 is selected from F, CnF2n+1,
OCnF2n+1, and OCF2X, where n is an integer from 1 through 6 and X=H, Cl, or Br, and
A=C or N, provided that when A=N, there is no R1.
In another embodiment, the present invention is directed to substituted 2-phenylpyridine, phenylpyrimidine, and phenylquinoline precursor compounds from which the above Ir(III) compounds are made. The precursor compounds have a structure (II) or (III) below: 
where A and R1 through R8 are as defined in structure (I) above,
and R9 is H. 
where:
at least one of R10 through R19 is selected from F, CnF2n+1, OCnF2n+1, and OCF2X, where n=an integer between 1 and 6 and X is H, Cl, or Br, and R20 is H.
It is understood that there is free rotation about the phenyl-pyridine, phenyl-pyrimidine and the phenyl-quinoline bonds. However, for the discussion herein, the compounds will be described in terms of one orientation.
In another embodiment, the present invention is directed to an organic electronic device having at least one emitting layer comprising the above Ir(III) compound, or combinations of the above Ir(III) compounds.
As used herein, the term xe2x80x9ccompoundxe2x80x9d is intended to mean an electrically uncharged substance made up of molecules that further consist of atoms, wherein the atoms cannot be separated by physical means. The term xe2x80x9cligandxe2x80x9d is intended to mean a molecule, ion, or atom that is attached to the coordination sphere of a metallic ion. The term xe2x80x9ccomplexxe2x80x9d, when used as a noun, is intended to mean a compound having at least one metallic ion and at least one ligand. The term xe2x80x9cgroupxe2x80x9d is intended to mean a part of a compound, such a substituent in an organic compound or a ligand in a complex. The term xe2x80x9cfacialxe2x80x9d is intended to mean one isomer of a complex, Ma3b3, having octahedral geometry, in which the three xe2x80x9caxe2x80x9d groups are all adjacent, i.e. at the corners of one face of the octahedron. The term xe2x80x9cmeridionalxe2x80x9d is intended to mean one isomer of a complex, Ma3b3, having octahedral geometry, in which the three xe2x80x9caxe2x80x9d groups occupy three positions such that two are trans to each other. The phrase xe2x80x9cadjacent to,xe2x80x9d when used to refer to layers in a device, does not necessarily mean that one layer is immediately next to another layer. On the other hand, the phrase xe2x80x9cadjacent R groups,xe2x80x9d is used to refer to R groups that are next to each other in a chemical formula (i.e., R groups that are on atoms joined by a bond). The term xe2x80x9cphotoactivexe2x80x9d refers to any material that exhibits electroluminescence and/or photosensitivity. The term xe2x80x9c(H+F)xe2x80x9d is intended to mean all combinations of hydrogen and fluorine, including completely hydrogenated, partially fluorinated or perfluorinated substituents. By xe2x80x9cemission maximumxe2x80x9d is meant the wavelength, in nanometers, at which the maximum intensity of electroluminescence is obtained. Electroluminescence is generally measured in a diode structure, in which the material to be tested is sandwiched between two electrical contact layers and a voltage is applied. The light intensity and wavelength can be measured, for example, by a photodiode and a spectrograph, respectively.